Brake



April 7, 1931- E. G. GUNN 1,799,227

BRAKE Filed April 17. 1929 mama A... '1, 1931 PATENT orator;

m1: a; com; or mrcmn; wrscon'sm, ASSIGNOR- T THE NASHVMOEQO'RS, comma or KENOSHA, WISCONSIN; A conronerrononmn-mrnm;

BRAKE Application: filed? April 17;

Thispinventiom IBlZLlZBSrtO improvements in.- brakezmechanism for motor vehicles, and? more'z'particularlyy to. servo; brakes :operable in: either:- directioni of rotation? of the; wheel.-

Theeprinciparl Objectofrthe'invention is. to provider-a'mimprovedxandgsimplified.construetion wherebyat leastwone of theqanchor: pins normally formscai fixed pivot point. for'its respective shoe while in idle position, and yet limited radiallmoyement of the shoe relative to said anchor is permitted to position said shoe relative to the drum when the brake is applied.

j The invention may best be understood by reference to the accompanying drawing, in which The figure is a face view of a brake constructed in accordance therewith.

In the embodiment illustrated in the draw: ing, the brake drum is carried by the wheel in the usual manner, andthe backing plate 12 is mounted on the wheel spindle (not shown) and having the brake mechanism carried thereon.

The braking mechanism shown herein comprises two substantially similar shoes and 21 arranged in reversed position relative to each other, and suitably connected together at their unanchored ends as by a floating link 22. In the form shown, said link is provided with eccentric devices for adjusting the effective length thereof, as disclosed in detail in my copending application bearing Serial No. 343,585, filed March 1, 1929, but as said adjustment devices form no part of the present invention, detailed description thereof is omitted herein.

A pair of anchor pins or lugs are mounted in spaced relation on the backing plate 12, one pin 16 serving the shoe 20 and the other pin 17 similarly serving shoe 21. The shoes 20 and 21 are provided withslots 20a and 21a respectively, through which the pins project, said slots in this case being elongated circumferentially of the drum, and also having rel atively wide end bearing surfaces, so to permit radial sliding movement of the shoes relative to their respective pins when in anchoring engagement therewith.

Braking pressure is applied to the shoes by 1929.4 serial: Nor. 355,732.:

any suitable. spreading; device, in .the. form shown, said device being, indicated generally;- at 40' and' disposed generally. between. the. anchore'd. endsof's'aid shoes. The. equalizer deviceJlOifsio eratedbya shaftddextending through the 'acliing plate-12'. and. having a. cross. armA7, thereon, A. pair ofequalizer links 48748 arepivotally mounted at opposite end'softhe. cross arm 47., said. equalizer links being; eachv provided. with opposed m curved. surfaces 4:9.4;9' which normally. en.- gage each other. onaline coincident withlthe axis of the ope'rating shaft.4t6,,as.shown in thefigure. The arrangement is .sueh thatv rotation .of. the operatingshaft. 4r6,the equal; izer links.4:8; l8l tend. to. spread apart, but said links may be. spread more in, one direc. tion than the. other, dependingupon the direction of the. rotation ofthedrum, but mains tainiiig substantially uniform pressure upon 70.. the shoesthrough the rollingfaction. of the engagedsurfaces4e9-49h V j v Referring now more. particularly to, the features. forming; the suhj ect matter 1 of the present invention; .I. provide .a. lever. 37-piV- oted. on shoe. 21 adjacent the inner 1 margin .of slot 21axandhaving one. endprojecting into engagement; with. the. anchor pin. 17 in a generaldirection tending to urgethe shoe-21 away from the ,drum, and', also maintaining saidl shoe. in anchoring engagement. relative to. saidlpin, as. clearlyshown .in'the figure of the drawing Suitable. tension is applied'to thelever fortlii'spurpose, in theform shown; a. spring' itl. being, connected to. the, other shoe 20 :so as to. providealso the sole tension means tending. normallyltofihold. the shoesin idle contracted position against stops 18, 18 carriedby. the backing plate. l V

The constructionabove described. is pan ticularly designedfor. a .wl1eel,rotating;n0r-' mallyr in a counterclockwise direction. in which; case. pin 17 forms the. anchor. for. the system, although ofi course, servo. action is also provided intheopposite; direction in case of reversal. of the wheeL. -However-,,as most Iofthe; brakingeffortris usually-required inone direction. only, but-one shoe 21, is here shown as provided with a; positioning lever 37.

The operation of the device is as follows:

With the wheel and drum rotating in a counterclockwise direction as above suggested, the shoes are normally maintained in contracted and idle position by spring 31, and by action of lever 37 against anchor pin 17, the anchored end of shoe 21 is urged away from the drum. In this position, pin 17 forms a substantially fixed point for pivotal movement of said shoe, until the brake is applied. When the brakes are applied, and pin 17 takes the braking thrust from shoe 21, the thrust is sufficient to overcome the tension of spring 31 acting through lever 37, and permit the shoe to move radially along the pin 17 as necessary to position itself automatically in concentric relation with the drum. When braking pressure is relieved, the parts return to their initial idle position, as shown.

It will be further noted, that the pin 17 is normally maintained in position at one end of the slot 21a so as to immediately take the thrust of said shoe at the instant the brakes are applied, and thus eliminate any shock or noise which would result if the shoe were floating loosely on the pin, as for instance, in the case with shoe 20 on pin 16. It is manifest that a similar lever could be furnished for shoe 20, if desired, but as already explained above, the added complication may readily be dispensed with on account of the fact that such brakes are used so little in the reverse direction, that an occasional noise from this source is not usually objectionable.

I claim as my invention:

1. In a brake, a drum, two shoes and anchor means therefor aiiordin servo action in either direction of rotation 0 said drum, one of said shoes having a slot in which its respective anchor is engaged, and a lever pivotally mounted on said shoe and yieldingly engaging said anchor in a direction opposed to the braking thrust of said shoe.

2. In a brake, a drum, two shoes and anchor means therefor affording servo action chor means therefor affording servo action in either direction of rotation of said drum, one of said shoes having an enlarged slot in which its respective anchor is engaged to permit radial movement of said shoe relative to said anchor, and a lever pivotally mounted on said shoe and yieldingly acting on said anchor in a direction opposed to the braking thrust of said shoe and to urge said shoe away from the drum.

5. In a brake, a drum, two shoes and anchor means therefor affording servo action in either direction of rotation of said drum, one of said shoes having an enlarged slot in which its respective anchor is engaged to permit radial movement of said shoe relative to said anchor, a lever pivotally mounted on said shoe and acting on said anchor in a direction opposed to the braking thrust of said shoe and to urge said shoe away from the drum, and a tension spring connected between said lever and the opposite shoe.

Signed at Racine this 1th day of April, 29.

EARL G. GUNN.

in either direction of rotation of said drum,

one of said shoes having a slot in which its respective anchor is engaged, a lever pivotally mounted on said shoe and acting on said anchor in a direction opposed to the braking thrust of said shoe, and a tension spring connlected between said lever and the opposite s 0e.

3. In a brake, a drum, two shoes and anchor means therefor affording servo action in either direction of rotation of said drum, one of said shoes having a slot in which its respective anchor is engaged, a lever pivotally mounted on said shoe and acting on said anchor in a direction opposed to the braking thrust of said shoe, and a tension spring connected between said lever and the opposite shoe, said spring forming the sole means for contracting said shoes.

4. In a brake, a drum, two shoes and an- 

